1. Field of the Invention
The present invention relates to a system and method that stores data for non-mainframe file systems on mainframe storage systems and that allows such data to be accessed by mainframe or non-mainframe file systems and connectivity.
2. Discussion of Related Art
The projected growth of storage for the coming years is staggering. Most of the growth is expected to be in xe2x80x9copen systemsxe2x80x9d architectures and devices. Open systems storage, however, is considered to have certain shortcomings, concerning (a) disk reliability, (b) the robustness and richness of data management software, (c) data management functionality, (d) system reliability, and (e) performance. On the other hand, mainframe storage systems are believed to address the above concerns favorably.
Open systems maintain data on open system disks using open system file systems like NTFS or UNIX (SUN/Solaris). Open system access their data using SCSI or fibre channel (FC) connectivity. Typically, servers access storage by specifying a device number a sector number and number of sectors to read/write. Each sector is typically 512 bytes. Typical file systems include a file directory table and a disk free space table along with other forms of xe2x80x9cmeta dataxe2x80x9d (i.e., information about the files themselves in contrast to the file""s data). Each file has an entry in the file directory table that specifies the file""s name and the physical locations where the file""s data is stored. Typically, the physical locations are specified as a set of fixed-sized sectors (a cluster in NTFS terminology). The disk free space table specifies physical locations of free sectors or clusters, i.e., areas of storage that are currently free to be used by the file system.
Mainframes maintain their data on mainframe storage systems using file systems like PS and VSAM. Mainframes manage their file systems through tools like SMS, HSM, and DFDSS. Mainframes access their data using ESCON connectivity. Mainframes typically organize storage as tracks (e.g., a complete circular section of a disk), cylinders (e.g., 15 stacked tracks corresponding to 15 stacked disk plates), and blocks, which can vary in size from as little as about 12 bytes to as large as about 56 kilobytes. Typical file systems include a file directory table and a disk free space table along with other forms of xe2x80x9cmeta data.xe2x80x9d Each file has an entry in the file directory table (e.g., VTOC) that specifies the file""s name and the physical locations where the file""s data is stored. Typically, the physical locations are specified as blocks in tracks, or more specifically, by the cylinder, block, and head numbers. Each block may be arranged in CKD form, which specifies the count, key, and data. The disk free space table specifies free tracks of mainframe disks.
The present invention provides systems and methods of servicing requests of a first file system communicated in accordance with a first storage protocol using a storage system that is responsive to requests communicated according to a second storage protocol and that is organized in accordance with a second file system. Among other things, this allows the use of potentially more reliable and robust storage systems for holding information of the first file system and allows potentially more reliable and robust management tools to manage the information of the first file system.
According to one aspect of the invention, a first portion of the storage system is allocated to hold data of the first file system. The first portion includes a set of locations for holding directory information of the first file system. A second portion of the storage system is allocated to hold data for the second file system. The second portion includes a set of locations for holding directory information of the second file system, including a set of file information entries corresponding to files of the first file system. Requests of the first file system are intercepted, and the intercepted requests are converted to corresponding requests in the second storage protocol. The conversion includes converting addressing information in the intercepted requests to addressing information in accordance with the second storage protocol. The converted requests are provided to the storage system so that the storage system may service the request. The intercepted requests are analyzed to determine if the requests are updating the set of locations holding directory information of the first file system. If so, corresponding update requests are constructed to update a corresponding file information entry in the second portion. In this fashion, the second portion includes entries that are consistent with the information in the first portion.